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Topic: 1st Yeast Harvest (Read 1607 times)

I did my first yeast harvest last week. As far as I can tell, everything went perfectly. To me, the samples look very good. I harvested WLP 001 Cali Ale Yeast. The one thing that I might have done incorrectly is that I harvested it off a Pliny brew. From what I have read, you really don't want to harvest it off of a real hoppy beer, because of the hop flavor. My plan was to harvest it off of a two-hearted clone, but I did not filter that from the brew pot to the carboy, so there was a lot of trub left behind in that. I filtered the Pliny with a leg stalking. It looked much cleaner to be able to harvest. I'm not too concerned about the hop flavor because this yeast will be used APA's and IPA's. I do have a few questions....

How many times can I re-harvest yeast?Does the yeast have better flavors further down the harvest line?How long will this harvest yeast keep in the fridge?As long as I keep re-harvesting this strain say at least once a month, will this yeast strain last forever, or will it die off over time?Does it look good?...These are 8 oz mason jars...

I would think the bigger concern with yeast from a pliny clone is that is a pretty big beer and the yeast are going to be a little stressed. Not really at their best. You might want to use a small amount of that yeast and make a start with it to increase the percentage of younger healthier cells in your population. (I could be wrong on this but some one will correct me if so)

There are differing opinions on how many times you can harvest. I know I have seen some brewers say the will to 10+ generations. others don't like to go more than 3 or so.

The yeast will evolve over generations and there for the flavour may change over time. this is one of the reasons for putting a limit on the number of generations you go if you are trying to maintain a known yeast character.

I would think it would be better to make a big starter, step it up a couple times even and then take part of that each time you brew rather than pitching the whole thing and re-havesting. This should reduce the drift in charcter over time because the dormant yeast in the fridge won't change as quickly as the yeast actively fermenting and being harvested and washed etc. and facing all the selective presures involved with that.

I agree with pretty much everything Mort said. I've not gone much beyond three generations on my harvests. I've also begun using sort of a "master" slurry like he describes, where I will take some yeast from my harvest and build up a starter to pitch in the next batch. I keep the bulk of the slurry in the fridge to use on subsequent batches and have not been reharvesting the same strain until/unless the slurry in the fridge is depleted.

As far as what you have harvested, I typically get much thicker slurries than what you show. Did you wash the yeast? I swirl my carboys and pour the slurry into tupperware containers. When they separate, I typically have 1/2 liter of yeast in a liter bottle.

I honestly didn't even think about the stress from the 8% ABV of the Pliny. I will be using a starter before pitching these again just to make sure. If they don't become active, I always have some SafAle 05 in the fridge as back up.

I did wash it. I used about 16-20 oz of sterilized water that I dumped into the drained carboy and shook it up. I poured what was left behind into two 32 oz mason jars, sealed and let sit for 45 minutes to an hour to let the trub settle out. I then poured off the liquid into these 4 mason jars. I could have filled a 5th jar, but I didn't have one ready to go.

A fellow homebrewer that I know has told me that the yeast really is at it's best after 4 or 5 brews. I'm sure this is completely up for debate and no conclusion will ever come lol.

As for yeast getting better/worse, I think it depends on the strain. Some tend to ferment faster in gen 2 or 3 but others tend to slow. As for flavor, that depends upon your taste. I've gone as long as 7 generations but typically stay around 3-4 now.

I just repitch slurry and try to not overpitch, as it can create esters (Denny and others have explained that problem as essentially the yeast don't have to reproduce as much, so they metabolize the sugars and throw off esters). For lagers of equal strength and volume, I try to repitch a half slurry at one month from prior repitch and for ales, about a third.

Generational improvement definitely seems to occur IMHO at least through 4-5 generations on many lager yeasts. I don't know how many times I have repitched my current batch of WLP800 and 34/70 strains, but I have brewed lagers a couple times a month for over 8 months now. I will pull up when a strain comes out that I want to try (like White Labs Munich Helles this spring) and then run that for a few batches....YMMV.